The present invention relates to a sealing device between the shaft and the housing of a turbo-machine having at least one rotor disk and, more particularly, to a sealing device which incorporates a gradation of the shaft lead-through bore to avoid wear of the sealing rings.
A known sealing device used on turbo-machines utilizes sealing rings which do not move in the circumferential direction and, together with an assigned ring groove in the rotating shaft, form a labyrinth seal, for the purpose of preventing lubricating oil leaking out of the bearing points of the shaft and moving delivered medium from the rotor disk space into the bearing points.
Such a known sealing device is shown in DE 32 19 127 C2 in with the pressure in the sealing gas space presses one sealing ring against the lateral flank of its ring groove facing away from the rotor disk. After an initial wear at the sealing ring with respect to the lateral flank of the ring groove, the sealing ring is pushed against a rectangular gradation of the shaft lead-through bore and stops the wear at the sealing ring.
The conventional sealing ring which serves as a boundary of the sealing gas space with respect to the rotor risk space normally is axially balanced between the pressure in the sealing gas space and the pressure in the rotor disk duct without coming in contact with one of the lateral flanks of the ring groove so that no wear occurs at the ring.
During a malfunctioning of the sealing gas supply, however, the sealing ring adjacent to the rotor disk space is axially shifted toward the sealing gas space by the pressure of the delivered medium existing in the rotor disk space and places itself against the groove flank of the ring groove facing away from the rotor disk space. Since an axial stop for that sealing ring is absent in the shaft lead-through bore, the malfunctioning of the sealing gas supply results in a wear which endangers the operation and may result in a total loss of the sealing ring.
It is therefore an object of the present invention to provide a sealing device for bounding a sealing gas space between a shaft and a housing of a turbo-machine in which a wear of the sealing rings which endangers the turbo-machine operation is avoided, and the malfunctioning of the sealing gas supply is largely avoided.
The foregoing object has been achieved in accordance with the present invention by arranging two sealing rings next to one another in a common ring groove of the rotor disk shaft and at least one radial groove is provided on the sealing rings on lateral flanges thereof facing one another. The joint between the mutually opposite lateral flanks of the sealing rings is arranged in the area of a circumferential groove forming a sealing-gas distributing space.
Principal advantages achieved by the present invention include the fact that the sealing ring on the rotor disk side can be supported at the gradation of the shaft lead-through bore and, when the sealing gas pressure is insufficient, is protected from being worn down, which endangers the operation of the turbo-machine, and a simple mounting of the shaft with the inserted sealing rings lowers susceptibility to changing sealing gas pressure so that the identical design of the sealing ring lowers the costs. Furthermore, procurement and stockkeeping of spare parts is reduced, and, as a result of the common ring groove for both sealing rings, the number of grooves flanks to be machined is reduced and results in lower shaft manufacturing costs.